Local soft tissue deficits often follow tooth loss and implant therapy. Under these circumstances, future implant reconstructions should aim to completely or at least partially compensate this loss in order to minimize any adverse effects, namely compromising subjective patient comfort. In the main, this encompasses disconcerting food impaction, as well as esthetic and phonetic impairment. The present article reviews the relevant prosthetically driven compensation measures, confining itself to the esthetic zone of partially dentate implant patients and fixed dental prostheses (FDP). In this specific context five objectives are of paramount importance: (I) establishing healthy peri-implant soft tissues, (II) avoiding open embrasures, (III) maintaining or recreating a harmoniously scalloped soft tissue course, (IV) achieving the optical illusion of balanced relative tooth dimensions, and (V) providing ease of access for effective plaque control. Six representative clinical examples featuring various degrees of peri-implant soft tissue deficiencies are addressed in detail, highlighting different design guidelines and pointing out their inherent limitations. In the case of minor-to-moderate soft tissue deficiencies, achieving the goal by implementing only morphological elements of the so-called white crown substrate such as adequate positioning of facial transition line angles and increased interdental contours is recommended. However, when facing major soft tissue deficiencies, the addition of pink ceramics as an integral part of the implant restoration may become unavoidable to achieve a clinically acceptable result. In this context one has also to take into consideration the position of a given patient’s individual smile line as an important decision-making parameter.
After tooth loss and subsequent implant placement, it is not uncommon for the clinician to face restoration sites featuring a deficit of soft tissue (Araujo & Lindhe 2005; Bidra & Chapokas 2011). The degree and three-dimensional configuration of the resulting peri-implant soft tissue deficiencies depend on both the local preoperative conditions and the surgical protocol used (Buser et al. 2013; Levine et al. 2014; Chappuis et al. 2016). These soft tissue deficiencies concern predominantly the interproximal “papillary” area, followed by mid-facial recessions (Tarnow et al. 2003; Buser et al. 2004). If the new implant-based restoration simply reproduced the originally present anatomical crown volume, it would logically result in open interdental embrasures or so-called “black triangles”. This, in turn, may significantly interfere with the patient’s subjective comfort. In posterior segments of the jaws, the main consequence of open embrasures is disconcerting food collection. In order to narrow down open embrasure space, restoration volumes are often increased to an unacceptable degree, leading to over-contoured design configurations that contradict the access required for plaque control.
When it comes to the esthetic zone, additional phonetic and esthetic problems arise. The latter is strongly dependent on the height of a given patient’s individual smile line and the degree to which the anterior maxillary alveolar process is exposed (Jensen et al. 1999).
In order to comply with the editorial space restrictions of the Forum Implantologicum, the focus of this article will confine itself to peri-implant soft tissue deficiencies located in the esthetically relevant zone of partially dentate implant patients and review their prosthetically driven compensation techniques.
Negative visual tension arises mainly if the alveolar mucosa is largely exposed during the patient’s unforced smile and one or several of the following conditions are present:
- Irregular course of the mucosal line. This points to an absence or interruption of a continuous and harmoniously scalloped soft tissue course. In fact, abrupt vertical position changes of the mucosal margin between neighboring sites are particularly disturbing.
- Open interdental spaces, also widely termed “black triangles”. Such open embrasures not only favor food retention, but they also adversely affect esthetic appearance and frequently cause speech impairment.
- Imbalance of relative tooth dimensions. This describes unnatural length-to-width ratios of clinical crowns, a phenomenon that is often the direct consequence of a lack of peri-implant soft tissue (Sterrett et al. 1999; Magne et al. 2003).
As previously mentioned, the scope of this article discusses only restoration-driven techniques to compensate peri-implant soft tissue deficiencies as the surgical possibilities are specifically presented in two other articles in this issue of Forum Implantologicum. Although the purely implant-prosthetic measures are clearly limited, it is not infrequent that they can still help to predictably transform an originally quite compromised situation into one that is acceptable to many patients (Garber & Belser 1995; Belser et al. 1996; Belser et al. 1998; Gallucci et al. 2004; Belser et al. 2006; Vailati & Belser 2007; Spear 2008; Belser et al. 2009; Gallucci et al. 2011; Buser et al. 2013; Wittneben et al. 2013; Boardman et al. 2016; Furze et al. 2016; Moraguez et al. 2016; Tettamanti et al. 2016). One should not forget that the restorative approach clearly helps to reduce the time, cost and complexity of the treatment. Furthermore, it avoids the inherent risk and morbidity of sophisticated surgical interventions. A typical clinical example where this strategy has been implemented is presented in Figs 1a - f.
In general, implant-prosthetic compensation techniques contribute to the following fundamental treatment objectives:
- Establishing healthy stable peri-implant tissue conditions and contours
- Avoiding or minimizing open embrasure spaces
- Maintaining or recreating a regular, continuous and harmoniously scalloped mucosal course
- Achieving the optical illusion of balanced relative tooth dimensions
- Providing ease of access for effective daily plaque control